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(a) The relationship between the concentration of various sulfur species (H2S, HS⁻ and S⁻) and pH value in Na2S solution. (b) Current response on the electrode with additions of various concentration H2S at 0.1 V in 0.1 M PBS solution (pH=7.4). (c) Corresponding calibration plot of Ti3C2Tx MXene/GCE on continuous additions of H2S. Error bars=Standard deviation (n=3).
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The layered structure of the two‐dimensional transition metal carbon/nitride and its excellent physical and chemical properties make it a major research hotspot in the field of sensing. Meanwhile, the characteristics of good biocompatibility and hydrophilicity make this type of material a very potential biological sensing material. In this work, a...
Citations
... After the discovery of grapheme [24], many-layered compounds have a considerable surface area to volume ratio, such as transition metal dichalcogenides (TMDs) [25], e.g. MoS 2 , WSe 2 , etc [26][27][28], MXenes [29], e.g. Ti 3 C 2 T x and MBenes [30], etc have been found to display great capability to sense H 2 S. The theoretical study of gas sensing helps explain electronic interaction at atomic and subatomic scales between the absorbent and analyte to enlighten suitably suggestive knowhows behind the phenomenon. ...
A notable surge in research interest directed towards the exploration and development of two-dimensional materials, specifically in the realm of advancing nano-devices, with a special focus on applications in gas detection, has been observed. Among these materials, the spotlight has fallen on a newly synthesized single-layered Dirac Semimetal, known as BeN4, which holds great promise as a potential candidate for an efficient gas sensor. The current investigation uses first-principles calculations to examine the H2S detection capability of pristine and point-defect-tempted BeN4 single-layers. The H2S molecule has been observed to be weakly adsorbed on pure BeN4 through weak van der Waals interaction exhibiting very low adsorption energy of −0.0726 eV and insignificant charge transport. The impact of the Be vacancy point defect in BeN4 was the surge in H2S adsorption energy to −0.582 eV, manifested by enhanced charge transmission (0.02 e) from the H2S molecule to the BeN4 with Be defects. The reasonable physical steadiness and modest recovery time (6 ms) at ambient conditions indicate the possibility of Be point-defected BeN4 being a contender as a sensor material for designing and developing a robust H2S gas sensor. In addition, the sensor exhibited a selective response towards the H2S gas molecules. Our findings will provide a reference line for the fabrication of innovative H2S detectors, showcasing the practical implications of the observed enhancements in H2S adsorption energy and charge transmission in Be point-defected BeN4 structures.
... Nevertheless, these methods are unsuitable for detecting H 2 S in biological samples due to the disadvantages of complicated operation, high cost, and timeconsuming processes. [22][23][24][25][26][27][28][29] Electrochemical analysis has the characteristics of high sensitivity, good selectivity and rapid detection, making it the most suitable method for detecting endogenous H 2 S. [30][31][32][33][34] Fortunately, H 2 S can be directly electrooxidized into products such as sulfur due to electroactivity. ...
... The practical feasibility of the sensor for detecting H 2 S in biological samples is verified by adding 15 % fetal bovine serum to PBS solution (pH = 7.4, 0.1 M) to simulate the biological environment. [22] The linear calibration curves of different concentrations of H 2 S in fetal bovine serum environment are shown in Figure S7. In the range of 10 to 258 μM, the current response is positively correlated with the concentration of H 2 S. The linear regression equation is I (μA) = 0.1978 [H 2 S] (μA · μM À 1 ) + 16.9208, and R 2 = 0.9901. ...
A one‐step hydrothermal synthesis method was used to synthesize ferric oxide nanoparticles with unique hollow spindle microstructure, which were mixed with conductive carbon black (CCB) to construct an electrochemical sensor to realize the highly sensitive detection of trace hydrogen sulfide (H2S) in biological samples. Our findings suggested that hollow spindle ferric oxide (Hs‐Fe2O3) held good electrocatalytic activity toward H2S, which mainly depended on the coupling effect of Fe (III)/Fe (II) significantly reduced the overpotential of electro‐oxidation reaction of H2S. Importantly, the unique structure of the hollow spindle provided more catalytic active sites and more efficient mass transfer process, which effectively improved the detection performance. The proposed sensor had good sensing performances, with excellent sensitivity (2.4 times of commercial Fe2O3/CCB), low detection limit (1.86 μM), wide linear range (7.6~152 μM) and favorable selectivity. Furthermore, quantitative detection of H2S was achieved in fetal bovine serum samples, which confirmed that the sensor could become a promising strategy for detecting H2S in the pathological study of related diseases.
... Accordingly, Fig. 6a shows the typical linear sweep voltammetry (LSV) of Ce/CeO 2 -rGO beyond the potential range of −0.55 V to 1.1 V vs. SCE; the increase in the current originates from the oxidation of the H 2 S. Herein, in Fig. 6a curve (iii) a small oxidation peak was observed for the changes in an oxidation state of Ce metal, i.e., from Ce +2 to Ce +3 . LSV on the prepared Ce/CeO 2 -rGO in the presence of H 2 S was performed to examine electrocatalytic sensitivity towards oxidation of H 2 S. Practically, in 0.5 M KOH, all H 2 S species convert to HS − , as it follows the first acid dissociation of H 2 S molecules and is schematically shown in Scheme 2 and is also reported elsewhere for similar systems [55][56][57][58][59]. Hydrogen sulfide is a weak acid and first dissociates H 2 S gas (H 2 S ↔ H + + HS − ↔ 2H + + S 2− ). ...
... Furthermore, the influence of the scan rate on the electrocatalytic oxidation peak potential (E pa ) and peak current for H 2 S at 2 ppm concentration on Ce/CeO 2 -rGO in 0.5 KOH was studied using LSV as shown in Fig. 6c. The current density variation along with a positive shift in potential values was found with an increase in the scan rate from 10 to 100 mV/s and also with a concentration corresponding to diffusion-controlled electron transfer, while here current density increases peak was broadly observed and is in good agreement with the literature [55][56][57][58][59][60][61]. ...
... The probable reaction mechanism is remarkably different when the Ce/CeO 2 -rGO is in a KOH electrolyte with different pH. When the Ce/CeO 2 -rGO is exposed to high pH, i.e., pH > 7, a huge number of active sites are available; hence, chemisorption dominates and this is the beginning of H 2 S adsorption [58,59]. ...
Herein, cerium/cerium oxide nanoparticles have been decorated on reduced graphene oxide (Ce/CeO2-rGO) for room temperature electrochemical determination of H2S in 0.5 M KOH. There is a superior linear correlation between the peak current density and H2S content in the tested range of 1–5 ppm. Moreover, comparison to other abundant gases such as CO2 shows no response at the potential of H2S oxidation, confirming no interference with H2S detection. It also reveals that the Ce/CeO2-rGO nanocomposite is a highly selective and sensitive system for the determination of H2S gas. Ce/CeO2-rGO synthesized by a simple chemical approach and further characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission-scanning electron microscopy (FE-SEM), coupled energy dispersive analysis of X-ray (EDAX), and BET-surface area measurement confirms the porosity of synthesized nanomaterials and homogeneous decoration of Ce/CeO2 nanoparticles on rGO sheets. The electrochemical studies, i.e., linear sweep voltammetry (LSV), of Ce/CeO2-rGO demonstrate the electrochemical H2S sensing at room temperature and for lower gas concentration (1 ppm) detection. The sensing mechanism is believed to be based on the modulation of the current and applied potential path across the electron exchange between the cerium oxide and rGO sites when exposed to H2S.
One-pot synthesis of Ce/CeO2-GO hybrid nanostructure is of immense significance for H2S gas sensors. Here is a new superficial synthetic way intended for the synthesis of Ce/CeO2-GO nanocomposites through the sol–gel technique. Herein, we depict that the consequential Ce/CeO2 NPs decorated on graphene oxide sheet material can give competent electrocatalysts for the H2S oxidation reaction in an alkaline condition. The current density of 5.9 mA/cm2 on the tiny potential of 2.5 mV vs. SCE demonstrates huge catalytic bustle and stability.
... Due to the metalloid nature of V 2 CT x MXene, charge redistribution at the heterojunction interface facilitating charge transfer, and enhanced NO adsorption energy at the heterojunction interface, the MOF@V 2 CT x heterostructures exhibited significantly improved electrochemical NO sensing performance compared to those of bare MXene and MOF. H 2 S is another endogenous gasotransmitter that is widely distributed in the body and plays an important role in neurotransmission, antioxidation, and vascular tone regulation [94,98]. Abnormal H 2 S concentrations may be related to neurodegeneractive disorders, gastrointestinal diseases, diabetes and cancer [98,99]. ...
... Abnormal H 2 S concentrations may be related to neurodegeneractive disorders, gastrointestinal diseases, diabetes and cancer [98,99]. A direct electrochemical sensor based on Ti 3 C 2 T x MXene-modified GCE was fabricated for H 2 S detection [94], which exhibited good sensing performance with a low LOD of 16.0 nM and a wide detection range from 100 nM to 300 µM. This work pioneered the use of MXene for H 2 S electrochemical sensing. ...
... H2S is another endogenous gasotransmitter that is widely distributed in the body a plays an important role in neurotransmission, antioxidation, and vascular tone regulati [94,98]. Abnormal H2S concentrations may be related to neurodegeneractive disorde gastrointestinal diseases, diabetes and cancer [98,99]. ...
Neurotransmitters are chemical messengers that play an important role in the nervous system's control of the body's physiological state and behaviour. Abnormal levels of neurotransmitters are closely associated with some mental disorders. Therefore, accurate analysis of neurotransmitters is of great clinical importance. Electrochemical sensors have shown bright application prospects in the detection of neurotransmitters. In recent years, MXene has been increasingly used to prepare electrode materials for fabricating electrochemical neurotransmitter sensors due to its excellent physicochemical properties. This paper systematically introduces the advances in MXene-based electrochemical (bio)sensors for the detection of neurotransmitters (including dopamine, serotonin, epinephrine, norepinephrine, tyrosine, NO, and H2S), with a focus on their strategies for improving the electrochemical properties of MXene-based electrode materials, and provides the current challenges and future prospects for MXene-based electrochemical neurotransmitter sensors.
... This was a big improvement over the previous H 2 S gas sensor. In 2021, Liu et al. [71] successfully synthesized multilayer Ti 3 C 2 T x MXene graphene-like structure by simple hydrogen fluoride etching method and fabricated it on glass carbon electrode (GCE) for electrochemical detection of H 2 S in biological environment. The layered structure of the two-dimensional transition metal carbon/nitide has the advantages of good conductivity and large specific surface area, providing more reaction sites. ...
As the third gasotransmitter, hydrogen sulfide (H2S) is involved in a variety of physiological and pathological processes wherein abnormal levels of H2S indicate various diseases. Therefore, an efficient and reliable monitoring of H2S concentration in organisms and living cells is of great significance. Of diverse detection technologies, electrochemical sensors possess the unique advantages of miniaturization, fast detection, and high sensitivity, while the fluorescent and colorimetric ones exhibit exclusive visualization. All these chemical sensors are expected to be leveraged for H2S detection in organisms and living cells, thus offering promising options for wearable devices. In this paper, the chemical sensors used to detect H2S in the last 10 years are reviewed based on the different properties (metal affinity, reducibility, and nucleophilicity) of H2S, simultaneously summarizing the detection materials, methods, linear range, detection limits, selectivity, etc. Meanwhile, the existing problems of such sensors and possible solutions are put forward. This review indicates that these types of chemical sensors competently serve as specific, accurate, highly selective, and sensitive sensor platforms for H2S detection in organisms and living cells.
... However, despite the promising results, MXene-based gas sensors are still in their infancy and limited to sensors with a small response, constrained detection diversity with usually poor selectivity to the target gas. For example, to the best of our knowledge, only one H 2 S gas sensor and one electrochemical H 2 S sensor based on the Ti 3 C 2 T x -related materials have been reported thus far 20,21 in which the sensing response for the gas sensor was mainly attributed to the Ag nanoparticles. Moreover, the intriguing role of intrinsic surface functional groups in the gas sensing performance has not been evaluated extensively even with theoretical calculations, which impairs the understanding of the sensing mechanism. ...
Cost-effective and high-performance H2S sensors are required for human health and environmental monitoring. 2D transition-metal carbides and nitrides (MXenes) are appealing candidates for gas sensing due to good conductivity and abundant surface functional groups but have been studied primarily for detecting NH3 and VOCs, with generally positive responses that are not highly selective to the target gases. Here, we report on a negative response of pristine Ti3C2Tx thin films for H2S gas sensing (in contrast to the other tested gases) and further optimization of the sensor performance using a composite of Ti3C2Tx flakes and conjugated polymers (poly[3,6-diamino-10-methylacridinium chloride-co-3,6-diaminoacridine-squaraine], PDS-Cl) with polar charged nitrogen. The composite, preserving the high selectivity of pristine Ti3C2Tx, exhibits an H2S sensing response of 2% at 5 ppm (a thirtyfold sensing enhancement) and a low limit of detection of 500 ppb. In addition, our density functional theory calculations indicate that the mixture of MXene surface functional groups needs to be taken into account to describe the sensing mechanism and the selectivity of the sensor in agreement with the experimental results. Thus, this report extends the application range of MXene-based composites to H2S sensors and deepens the understanding of their gas sensing mechanisms.
Since the discovery, MXenes has gotten a special attention as 2D functional materials. The advanced applications are directly linked to its synthesis approaches, terminal groups (O, OH and F) and...
Abnormal sulfide levels in serum can cause kidney failure, Alzheimer's, Parkinson's, stroke, diabetes, and even cancer. Therefore, maintaining proper sulfide balance is crucial for managing and preventing these conditions. Electrochemical approaches have emerged as potential alternatives for sulfide detection. However, the adsorption of elemental sulfur on the working electrode leads to surface fouling and passivation, posing a significant challenge in developing reliable electrochemical methods for sulfide detection. In this study, we present a portable and surface fouling-free electrochemical system that utilizes functionalized multi-walled carbon nanotubes and 4-aminophenylboronic acid dimers for accurate sulfide measurement. The sensor showed excellent electrocatalytic activity to sulfide and antifouling activity to possible interferences. The method had a linear range from 10 µM to 2 mM and a detection limit of 2.3 µM. The effectiveness and applicability of this method were evaluated by analyzing sulfide levels in different serum samples and comparing the results with their glucose levels. As both blood glucose and sulfide levels can serve as indicators of certain health conditions, such as diabetes or sulfur metabolism disorders, this comparison provides valuable insights. Importantly, no complicated sample pretreatment was involved, thus this method can be easily adopted as a point-of-care diagnostic device. Additionally, the study also revealed a higher concentration of sulfide in cancer cells than in normal cells, offering a new development direction for differentiating between cancer cells and normal cells.
